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Aster junciformis Rydb. Bull.

Rush Aster

Asteraceae (Aster family)

Synonyms: Aster borealis (Torr. & Gray) Prov.; Symphyotrichum boreale (Torr. & Gray) A. & D. Love

General Description: Slender, erect perennial 30-80 cm tall from creeping rhizomes seldom over 2 mm thick. The stems are mostly glabrous except for lines of appressed pubescence decurrent from the leaf bases. The linear-shaped leaves are 4-11 cm long by 2-6 (rarely to 9) mm wide, entire or subentire, scabrous on the margins, sessile, and often slightly clasping at the base. The lowermost leaves are sometimes reduced and sub-petiolate, but then soon deciduous. Each plant has a few uncrowded, to occasionally many, flower heads (or solitary in reduced plants). Rays commonly 20-50, white to pale blue or lavender, and 7-15 mm long. The mostly acute, glabrous, imbricate involucre bracts are 5-7 mm high and often have purplish tips and margins.

Illustration.

Field Identification Tips: The very slender habit combined with its more or less linear leaves, generally few, uncrowded flower heads, and saturated wetland habitat, helps distinguish it from most other aster-like plants.

Phenology: Flowers late July to September.

Similar species: There are several other wetland habitat composite species that may look superficially similar, especially in Aster and Erigeron.

Habitat: Fens, bogs, springs, and wet meadows; typically where the substrate remains saturated year-round.

Global Distribution: Alaska, eastward to Quebec, and southward to Idaho, Colorado, Wyoming, Nebraska, South Dakota, Minnesota, and New Jersey.

Idaho Distribution: Known from four widely separated areas in the state - the Henrys Lake and Driggs areas in eastern Idaho, near Thousands Springs in east-central Idaho, the McCall area in west-central Idaho, and from the Panhandle region.

References:

Larsen, G. E. 1993. Aquatic and wetland vascular plants of the northern Great Plains. Gen. Tech. Rep. RM-238. U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Center, Fort Collins, CO. 681 pp.